Device for sealing an enclosure containing an expandable fluid, especially within an electrical connection assembly

A device for sealing an enclosure containing an expandable fluid, including at least one O-ring seal, the enclosure being constituted by the assembly of at least two components between which an internal space contains the expandable fluid, the seal being contained within an annular recess located between the two components about an axis of symmetry, said recess being adapted to communicate with the internal space, said seal being clamped between two opposite walls of said recess, wherein provision is made along the section of the annular recess for a length L1 in which the seal is capable of moving and of occupying n positions, the length L1 of the annular recess being constituted by an initial clamping space and by a clearance space, the initial clamping space being such as to correspond to an initial first position P1 of the seal and the clearance space being located on one side of the seal which is remote from the internal space so that the seal penetrates into said clearance space under the pressure of the expanded fluid, the two components between which the annular recess is formed being constituted by a female component and a male component of which the body is engaged in said female component, the male and female components being such as to form a high-voltage electrical connection assembly, the internal space being defined between the body of the male component and the internal surface of the female component, the male and female components being provided respectively with a first and a second annular attachment flange between which is disposed the annular recess containing the seal.